diff --git a/pkgs/applications/video/mplayer2/default.nix b/pkgs/applications/video/mplayer2/default.nix
index a1e930d57d5..5827e22ea5e 100644
--- a/pkgs/applications/video/mplayer2/default.nix
+++ b/pkgs/applications/video/mplayer2/default.nix
@@ -113,8 +113,8 @@ stdenv.mkDerivation rec {
       ${optionalString (stdenv.isi686 || stdenv.isx86_64) "--enable-runtime-cpudetection"}
       ${optionalString dvdnavSupport "--extra-ldflags=-ldvdread"}
       ${if xvSupport then "--enable-xv" else "--disable-xv"}
-      ${if x11Support then "--enable-x11 --enable-gl --extra-cflags=-I{libx11}/include"
-		else "--disable-x11 --disable-gl"}
+      ${if x11Support then "--enable-x11 --enable-gl --extra-cflags=-I${libX11}/include"
+        else "--disable-x11 --disable-gl"}
       --disable-xvid
       --disable-ossaudio
     '';